Locking attachment for vault doors



Aprill l5, 1930. A. EVENSEN I I 1,754,386

. I v I |OCKING ATTACHMENT FOR VAULT DOORS I Filed May 24. 1928 3 Shets-Sheet 1 April 15, 1930. V I A. EvfiqjsEN T I 1,754,386

' LOCKING ATTACHMENT FOR VAULT DOORS I Filed May 24, 1928 3 Sheets-She et 2.

April 15, 1930.

A. EVENSEN LOCKING ATTACHMENT FOR VAULT DOORS Filed Ma 24, 1928 5 Sheets-Sheet 3 III Z7? #9 72 20 r.- flnion K249775622,

Patented Apr. 15, 1930 PATENT OFFICE ANTON EVENSEN, OF FOX LAKE, ILLINOIS LOCKING ATTACHMENT FOR VAULT DOORS Application filed May 24,

This invention relates to improvements in vault door constructions and more particularly to an attachment for automatically looking a vault door in almost completely closed position and for automatically releasing the locking mechanism after a predetermined time.

It is a common occurrence in daylight robberies of banks for burglars to lock a bank employee in the vault, whereby his life may be endangered on account of lack of air. Devices have heretofore been provided for preventing vault door closing mechanism from being actuated, so that the employee cannot be locked in the vault, but such devices do not prevent the burglar from injuring his victim.

The object of the present invention is to provide an attachment for vault doors which, when the door has been moved almost to its closed position, will automatically lock the door in said position, and for a predetermined time, hold it in such position with respect .to the door frame that the burglar will be denied access to the vault and therefore be unable to injure the person locked therein, and

that the door will be sufficiently spaced from the door frame to admit air to the interior of the vault.

Another object is to providea timing-mechanism and bolt control mechanism which shall be simple in construction and function efficiently for their intended purpose of looking the door in partially closed'position for a predetermined time.

Another object of the invention is to produce a device adapted tobe attached to the inner surface of the door where it will be inconspicuous and may not be tampered with by persons attempting to close the door.

In the drawings:

Figure 1 is an elevation showing part of a vault door, which has been provided with an attachment embodying my invention, as viewed from the vault interior.

Figure 2 is a horizontal sectional view taken in the plane of the line 2-2 of Figure 1, looking in the direction indicated by the arrows.

Figure 3 is an enlarged sectional view taken on the line 3-3 of Figure 1, looking clown- 1928. Serial No. 280,204.

wardly, part of the control mechanism being omitted to more clearly show the underlying parts; said figure showing the position of the locking bolts and bolt control mechanism when the door has been almost completely closed and the bolts have been extended to engage the frame.

Figure 4 is a View similar to Figure 3,-but showing the position of the parts when the control mechanism is in inoperative position; that is, when not set for action.

Figure 5 is a view similar to Figure 3, but showing the position of the parts when the control mechanism has been key-operated so as be in position to act when the door is moved toward closed position.

Figure 6 is a vertical sectional view taken in the plane of the line 66 of Figure 4, looking in the direction indicated by the arrows.

Figure 7 is a transverse, vertical sectional view taken in the plane of the line 77 of Figure 6, looking in the. direction indicated by the arrows.

Figure 8 is a horizontal, sectional view taken in the plane of the line 8-8 of Figure 6, looking downwardly as indicated by the arrows.

Figure 9 is transverse, vertical sectional view taken in the plane of the line 99 of Figure 8, looking in the direction indicated by the arrows.

Figure 10 is a transverse, ver ical sectional view, taken in the plane of the line 1010 of Figure 8, looking in the direction indicated by the arrows.

Figure 11 is a fragmentary view showing the t am of gears between the timing mechanism and the door engaging mechanism for controlling the unwinding of the timing mechanism.

Figure 12 is a sectional view taken on the line 12-12 of Figure 11, looking in the direction indicated by the arrows.

Inthat embodiment of my invention shown in the drawings, 15 indicates the door and 16 the door amb or fixed portion of a vault construction. The door and frame have complemental angular edge surfaces indicated at 17 and 18, respectively, and the frame has a shoulder 19 against which the inside surface of the door 15 abuts when the door is completely closed. On the inner surface of the door 15 are the usual vertical bars 20, 21, in this instance integral with the door, and adjacent the bar 21 is positioned my automatic locking attachment, to which this invention is more particularly directed.

A cover or casing for the attachment is indicated at 22. It co-operates with a supple mental casing 23 to inclose the parts when in position on the door. The rear wall 24 of the supplemental casing 23 is bolted to the door 15 as indicated at 25.

The horizontally disposed surface of the casing 23 is cut away or recessed as indicated at 26, so that the upright wall 27 of a follower 28 located in the chamber 29 may extend upwardly into the chamber 30 above the chamber 29, and be movable in said recess 26. The horizontal wall of the supplemental casing 23 is also cut out or slotted as shown at 31 and 32 to accommodate a pair of vertically disposed bolt pins 33 and 34, rigidly connected to a pair of sliding bolts 35 and 36, respectively.

The bolts 35 and 36 are the door frame-engaging parts and will now be described. As shown. the bolts extend from the attachment through apertures in the door bar 21 and are movable therein. The bolt 35, which is the one farthest away from the door 15, is beveled at one end as indicated at 35' so that when it is attempted to close the door 15, the beveled surface 35' will contact with and slide over the shoulder 19 on the frame 16, the bolt 35 being pressed inwardly by said shoulder 19 until it has passed it. Both bolts 35 and 36 have inwardly extending portions 37, 38, of diminished iameters. The free ends of the parts 37 and 38 are slidably mounted in apertures in the left-hand upright wall of the follower 28, and the free ends of the larger bolt portions 35 and 36 extend through apertures in the opposite wall 39 of the follower 28, and then outwardly through apertures in the casing 23, and through the door bar 21. Coiled springs 40 and 41 surround the bolt members 37 and 38, respectively, the ends of the springs abutting against the upright end wall of the follower 28 and against the shoulder formed by the ends of the larger bolts 35 and 36 at their junction with the members 37 and 38, respectively.

It will be understood that the bolt members 37 -35 and 38-36, with the pins 33 and 34 attached to the parts 35 and 36, respectively, are located in the chamber 29 and that the normal tendency of the coiled springs 40 and 41 is to keep the bolt members outwardly extended to the limit of the movement permitted by the length of the slots 31 and 32 in the casing 23 through which the pins 33 and 34, respectively, extend.

Between the bolt members just described there is located in the chamber 29 a bolt 42 which is rigidly secured at each end in the supplemental casing 23, and extends near one end through an aperture in the upright wall of the follower 28 and at the opposite end over the depressed part of the follower wall 39. A coiled spring 43 surrounds the bolt 42, one end of the spring pressing against the follower 28 and the other end against the casing 23.

Part of the locking bolt control mechanism is located in the upper chamber 30 above the horizontal wall of the'casing 23. The numeral 44 indicates a housing containing a conventional timing mechanism, operatively connected to a rotatable shaft 45, suitably journaled in a support 46. The shaft 45 carries a pinion 47, the forward end of the shaft extending through an aperture in the casing 22 and constituting a key-operated winding arbor 48. The pinion 47 is in mesh with a gear 50 rotatably mounted on a shaft 51, journaled in a support 52. The gear 50 has attached to it a pin 53 extending rearwardly at right angles to the face of the gear 50.

Mounted on top of the horizontal wall of the casing 23 in such position that it may be engaged by the pin 53, is a lever 54 having a hooked arm 55 and a second arm 56, the end of which is provided with an upwardly extending pin 57. One side of the arm 56 is outwardly extended and curved as indicated at 54. The lever 54 is pivotally mounted on a screw bolt 58 secured to the casing 23.

Toward the opposite side of the chamber 29 on top of the supplemental casing 23, is a lever 59 pivotally mounted on the screw bolt 60. This lever has two arms, 61 and 62, adapted to contact with the pins 33 and 34, respectively. A spring 63 connected to the lever arm 62 and to the casing 23 functions to bring the arm 62 back to its intended position, as will be hereinafter explained, and a stop pin 64 limits the movement of the arm 62 when under influence of the spring 63.

The operation of the device is as follows:

Assuming that the parts of the control mechanism are in the inoperative position shown in Figures 4 and 6 and the door 15 is open as is customary during banking hours, the bank employee will insert a key into the winding arbor 48, and turn the key as far as possible. The shaft 45, which is operatively connected to the timing mechanism, will thereby wind or set the timing motor for operation. As shown in the drawings, this rotation of shaft 45 will be toward the right so that the pinion 47 in mesh with the gear 50 will drive said gear 50 and carry the pin 53 toward the left until said pin contacts with the wall 27 of the follower 28 extending upwardly through the recess 26 of the supplemental casing 23. The turning of the key in the winding arbor 48 will be continued until the pin 53 on gear 50 has moved the follower 28 by contact with its wall 27 to the limit of the movement permitted by the recess 26.

When the winding has been completed, the parts will have assumed the position shown in Figure 5, where the pin 53 has moved the follower wall 27 toward the inner side of the recess 26, which action has caused the follower wall 27 to contact with the cam surface 54, causing the lever 54 to move about its pivot 58 and the hooked arm 55 to engage the follower Wall 27 and to hold it in the position shown in said Figure 5.

The lever 59, being maintained in normal position by the spring 63, will be ready to contact with the pins 33, 34, respectively. The follower 28l1aving been moved toward the right by the pin 53 as heretofore explained (from the position shown in Figure 4 to that of Figure 5), the coiled springs 40, 41 and 43 2 will have been compressed and the bolts 35, 36,

will have been moved outwardly toward the right, but only to a very slight extent, the movement being limited for the reason that the rigidlyattached bolt pins 33 and 34, respectively, are stopped by the lever 59, as shown in Figure 5.

The position of the parts as shown in said Figure 5 is that which may be referred to as set, being the position resulting from winding the time mechanism heretofore descrlbed. The latter will be held against unwindlngby gears operatively connected with the slid ng bolt 36, and will be released by the actuating of said bolt when it is attempted to close the door. It will be understood that said time mechanism may be constructed so as to run down or unwind within any desired predetermined time, say half an hour.

When an unauthorized person attempts to close the vault door after the parts of the locking attachment are positioned as shown in Figure 5, the beveled end of the bolt 35 will first come inv contact with. the shoulder 19 on the door frame 16 and because of its beveled form, it will ride .over said shoulder and the bolt 35 will be pressed inwardly against the tension of the spring 40, the pin 33 will be moved to the left the slight distance aiforded by the slot 31, but sufiiciently to per- I mit the end of the arm 61 of the pivoted lever 59 to swing past the pin 33. Simultaneously, the lever arm 62 moves to the right, because it follows that when the arm 61 is released by the pin 33 the other pin 34 under the influence of the coiled spring 41 pushing against the bolt 36 to which the pin 34 is attached will exert pressure against said arm 62. The result is that the pin 34 travels to the outer no ,end of the slot 32, carrying the lever arm 62 with it; and under the influence of the spring 40, the bolt 35 and pin 33 will also be moved outwardly to the full extent permitted by the slot 31, so that the parts will assume the position shown in Figure 3, where the bolts are fully extended and holdthe door to the frame as shown in Figure '2.

It will be understood that this tripping action by the lever 59 of the bolts 35 and 36 is necessary because if the bolts were fully extended in the first instance under influence of the springs 40 and 41, it would be impossible to bring the door to the almost completely closed position desired. By the construction just described, the bolts 35 and 36 will be held in retracted position until the bolt 35 has passed the shoulder 19, inward pressure on said bolt 35 through its pin 33 tripping the lever 59 so that the pin 34 on bolt 36 is automatically released, permitting bolt 36 under influence of spring 41 to be fully extended, and at the same time bolt 35 with its pin 33 is moved outwardly under influence of spring 40 to the fullest extent, as shown in Figures 2 and 3. The bolt 35 prevents the door from being opened and the bolt 36 prevents it from being completely closed.

The door will be held in this almost closed position for a predetermined time depending on the arrangement of the timing device in the housing 44. The victim who may be locked in the vault will be protected against violence for said period and sufficient air will be admitted for his comfort.

The door cannot be opened until the unwinding of the timing device, set in motion by the actuating of bolt 36 in the act of closing the door (as will be more fully described at the close of the specification),

causes the pinion 47 on the shaft to re verse the movement of the gear 50 carrying the pin 53, so that said pin will be carried in a direction opposite to that transmitted to it in key-winding the device; that is to say, the pin 53 will be gradually carried upwardly away from the follower wall 27 and around until it contacts with the pin 57 on the lever 54, thereby moving the lever arm 56 toward the left and unhooking the hooked arm from the follower wall 27. The follower will then move quickly to the left under influence of the spring 43, and the control parts and bolts 35, 36,1esuine the position shown in Figure 4.

In Figure 11, I have shown the operative connections between the timing mechanism in the housing 44 and the pin 34 on the movable bolt 36 whereby the timing mechanism is prevented from unwinding until the door has been almost completely closed and the bolt 36 actuated. The parts about to be described are also shown in the vertical sectional view of Figure 6, but have been left out of the horizontal sectional views, Figures 3, 4 and 5, for the sake of clarity. The nu ineral indicates a train of gears operative" ly connecting the shaft .45 with a rotatable shaft 66. The shaft 66 carries a governor 67,

and near its end said shaft 66 is knurled for ill) iii)

frictional engagement with a spring 68 connected to the pin 34 on the movable bolt 36.

The function of this mechanism is as follows:

When the bolt 36 is in retracted position, as is the case when the locking device is inoperative, and when it has been set for operation but before the door has been moved to almost closed position, the spring 68 on the pin 34 will have frictional engagement with the knurled shaft 66 and through the train of gears 65 will prevent the shaft from rotating under influence of the unwinding action of the time controlled mechanism. \Vhen the bolt 36 has been actuated in the manner heretofore explained by the moving of the door to ahnost closed position, the out ward movement of said bolt 36 will carry the spring 68 away from the knurled shaft 66, leaving the time controlled mechanism in the housing 44 free to unwind or run down for the predetermined time. The unwinding will be controlled by the governor 67 During the unwinding, the shaft 45 is rotated in a direction the reverse of that by which it was wound, and through the pinion 47 will rotate the gear 50 carrying the pin 53 until said pin 53 contacts with the pin 57 on the lever 54, unhooking the arm 55 from the follower wall 27 and permit-ting the parts to resume the position shown in Figure 4 so that the door may be opened or completely closed, as desired.

Various modifications may be made without departing from the scope of my invention and I do not desire to be limited to the exact form and details of construction shown and described.

I claim as my invention:

1. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices.

2. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and time controlled means for releasing the tension on the frame engaging devices.

Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein. means for putting the fran'ie-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasin the tension on the frame-engaging devices, said frame-engaging devices comprising a pair of independently movable bolts.

4. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for main- 5:

taining the same under tension, means for holding said frame-engaging devices in re tracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said frame-engaging devices comprising a pair of independently movable bolts having stop pins rigidly secured thereto for contacting with said holding means.

5. Locking mechanism for vault doors for locking the door in almost completely closed position relat've to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retractcd position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means for putting the frameengaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower.

6. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means for putting the frame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for 1 moving the follower including a rotatable gear in operative engagement with the follower and means for actuating the gear.

7. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, ieans for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means for putting the frame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower, and said means for maintaining the frame-engaging devices under tension including a pivoted lever adapted to engage the follower.

8. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said f time-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on tne frame-engaging devices, said means for putting the frame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower, and said means for niaintainingthe frame-engaging devices under tension including a pivoted lever having a hooked arm for engaging, the follower.

9. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage theframe before the door is completely seated therein, means for putting the frame-engaging de vices under tension, means for maintaining. the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension of the frame-engaging devices, said means-for plitting the frame-engaging devices under tension: comprising a; follower,

yieldingimeans between-the follower and the" ra -en g ng d es nd mec ni m f9? moving the follower, and said means for maintaining the frame-engaging. devices under tension including a pivoted leverhaving a cam surface for contact with the follower and hooked arm for engaging the follower.

l0. Locking mechanism for vault doors for locking the door in almost; completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means, r ld ng th fr meens eins devices in retracted position including a pivoted lever.

11. Locking mechanism for vault doors; for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under' tension, means for maintaining the same under tension, means for holding said frame-engaging. devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging. devices, said frame-engaging devices comprising a pair of independently movable bolts having stop pins rigidly secured thereto for contacting with said holding means, said means for holding the frame-engaging devices in retracted position including a pivoted lever incontact with the pins on the movable bolts.

12. Looking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably' mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said fra1ne-engaging devices in retracted po-' sition, means for automatically tripping the holding means, and means for releasing the tension on the frame, engaging device's, said means for tripping the holding means being, actuated by inward pressure on theend: of one; of the; frame engaging devices it, contacts with the door frame;

13. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices: moi'iably mounted on the door, and arrangedto engage: the frame before the-door completely seated: therein,

means for putting the frame-engaging devices under tension, means for maintalning the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said tension releasing means including time-controlled mechanism operatively connected with the means for putting the frame-engaging devices under tension.

14. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means for putting the frame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower including a rotatable gear in operative engagement with the follower and means for actuating the gear, said tension releasing means including means for reversing the rotation of the followerengaging gear.

15. Looking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frameengaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein, means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frameengaging devices, said means for putting the lame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower including a rotatable gear in operative engagement with the follower and means for actuating the gear, said tension releasing means including time-controlled means for reversing the rotation of the follower engaging gear and means for returning the follower to normal position.

16. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, including frame-engaging devices movably mounted on the door, and arranged to engage the frame before the door is completely seated therein,

means for putting the frame-engaging devices under tension, means for maintaining the same under tension, means for holding said frame-engaging devices in retracted position, means for automatically tripping the holding means, and means for releasing the tension on the frame-engaging devices, said means for putting the frame-engaging devices under tension comprising a follower, yielding means between the follower and the frame-engaging devices, and mechanism for moving the follower including a rotatable gear in operative engagement with the follower and means for actuating the gear, said means for maintaining the frame-engaging devices under tension including a pivoted lever having a hooked arm for engaging the follower, and said tension releasing means including means for reversing the rotation of the follower-engaging gear and means for tripping the hooked arm lever.

17. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, comprising a casing fixed to the door, a pair of independently movable bolts mounted therein, a follower, yielding means between the follower and the movable bolts, mechanism for moving the follower, a pivoted lever adapted to engage the follower, a pivoted lever for engaging the movable bolts and time controlled mechanism for releasing the follower-engaging lever.

18. Locking mechanism for vault doors for locking the door in almost completely closed position relative to its frame, comprising a casing fixed to the door, a supplemental casing dividing said first mentioned casing into two chambers, a pair of bolts movably mounted in the casing having pins rigidly secured thereto and extending through slots in the casing, means for putting said bolts under tension comprising a follower extending through a recess in the supplemental casing and yielding means between the follower and said bolts, a pivoted lever mounted on the supplemental casing for engagement with the follower, a second pivoted lever mounted on the supplemental casing for engagement with said bolt pins, a gear havinga pin rigidly connected thereto for engaging the follower, a pin on the follower-engaging lever adapted to be engaged by the pin on the gear and time mechanism operatively connected with said gear.

19. In vault construction, a door, a frame having a flange extending longitudinally of the frame and toward the door and a locking device secured to the inside of the door, said locking device including a pair of independently movable bolts, means for placing same under tension, means for holding the bolts in retracted position, means operated by contact between one bolt and said frame flange for tripping the holding means, and means for releasing the tension on said bolts.

20. In vault construction, a door, a frame having a flange extending longitudinally of the frame and toward the door and a locking device secured to the inside of the door, saie locking device including a pair of independently movable bolts, means for placing same under tension, means for holding the bolts in retracted position, means operated by contact between one bolt and said frame flange for tripping the holding means, and time controlled means for releasing the tension on said bolts.

In testimony that I claim the foregoing as my invention I afiix my signature this 10th day of May, 19:28.

ANTON EVENSEN. 

